I run 4 - 5 on track events a year mostly at Carolina Motorsports Park and I am having some problems with vibration from the left front brake under hard braking.

Now I have installed the Cobra R 4 Piston calipers and rotors, and the 1st couple of events, no problems. After replacing pads, at the next track event I had a severe vibration in the left front under heavy braking (Turn 10 at CMP). Changed pads and put on a set of rotors that I had turned. Next event, slight vibration that was noticable under hard braking.

Now I am wondering if I might be having a wheel hub staring to go bad?